1. Field of the Invention
The invention relates to a battery current collector foil, a method of manufacturing the battery current collector foil, and a battery that uses the battery current collector foil.
2. Description of the Related Art
In recent years, with the widespread of portable electronic devices, such as cellular phones, notebook personal computers and video camcorders, and vehicles, such as hybrid electric vehicles, the need for batteries used in driving power supplies of these portable electronic devices and vehicles has been increasing. Some of the above batteries use a positive electrode current collector foil having an aluminum foil as a base material. The above batteries, for example, include lithium ion batteries that use a positive plate, which is formed by coating a positive electrode current collector foil having an aluminum foil as a base material with a positive electrode active material layer containing an Li chemical compound.
Incidentally, a coating made of aluminum oxide is formed on the surface of the aluminum foil. Thus, when a positive electrode current collector foil, in which an aluminum oxide coating is formed on the surface of the aluminum foil, is used and then a positive electrode active material layer is formed on the surface of the positive electrode current collector foil, conductivity between the aluminum foil and the positive electrode active material layer problematically decreases because of the influence of the aluminum oxide coating. To solve the above problem, there has been suggested a technique for forming a conductive coating made of carbon, or the like, by vapor deposition after the surface of the current, collector (aluminum foil) is subjected to dry etching (see, for example, Japanese Patent Application Publication No. 11-250900 (JP-A-11-250900)).
However, when the conductive coating made of carbon, or the like, is formed on the surface of the aluminum foil by vapor deposition, compression stress occurs in the vapor-deposited conductive coating. This compression stress acts on the aluminum foil. For this reason, a wrinkle may occur in the aluminum foil (positive electrode current collector foil). In addition, because of the influence of the wrinkle, it may be difficult to appropriately (uniformly) coat the surface of the positive electrode current collector foil with the positive electrode active material layer.